Aggregate transitions in mixtures of anionic sulfonate gemini surfactant with cationic ammonium single-chain surfactant.

Aggregation behaviors in mixtures of an anionic gemini surfactant 1,3-bis(N-dodecyl-N-propanesulfonate sodium)-propane (C(12)C(3)C(12)(SO(3))(2)) and a cationic single-chain surfactant cetyltrimethylammonium bromide (CTAB) have been investigated in aqueous solutions at pH 9.5 by turbidity, rheology, isothermal titration microcalorimetry (ITC), cryogenic transmission electron microscopy, and dynamic light scattering. Reversible aggregate transitions from spherical micelles to wormlike micelles, vesicles, and back to wormlike micelles and spherical micelles are successfully realized through fine regulation over the mixing ratio of surfactants, i.

Effects of calcium ions on solubility and aggregation behavior of an anionic sulfonate gemini surfactant in aqueous solutions.

Effects of calcium ions on the solubility and aggregation behavior of an anionic sulfonate gemini surfactant 1,3-bis(N-dodecyl-N-propylsulfonate sodium)-propane (12-3-12(SO(3))(2)) have been studied in aqueous solution. Compared with single-chain surfactant sodium dodecylsulfate, 12-3-12(SO(3))(2) shows much better performance to the hardness tolerance with calcium ions. Moreover aggregates of the Ca(2+)/12-3-12(SO(3))(2) complexes in clear solutions influence the morphologies of the precipitates.

Aggregate transitions in aqueous solutions of sodium dodecylsulfate with a "gemini-type" organic salt.

Effects of a "gemini-type" organic salt 1,2-bis(2-benzylammoniumethoxy) ethane dichloride (BEO) on the aggregation behavior of sodium dodecylsulfate (SDS) have been investigated by turbidity, surface tension, isothermal titration microcalorimetry, dynamic light scattering, cryogenic transmission electron microscopy, (1)H NMR spectroscopy, and differential scanning microcalorimetry. The aggregation behavior of the SDS/BEO mixed aqueous solution shows strong concentration and ratio dependence. For the SDS/BEO solution with a molar ratio of 5:1, large loose irregular aggregates, vesicles, and long thread-like micelles are formed in succession with the increase of the total SDS and BEO concentration.

Synthesis and aggregation behavior of a hexameric quaternary ammonium surfactant.

A star-shaped hexameric quaternary ammonium surfactant (PAHB), bearing six hydrophobic chains and six charged hydrophilic headgroups connected by an amide-type spacer group, was synthesized. The self-assembly behavior of the surfactant in aqueous solution was studied by surface tension, electrical conductivity, isothermal titration microcalorimetry, dynamic light scattering, cryogenic transmission electron microscopy, and NMR techniques. The results reveal that there are two critical aggregate concentrations during the process of aggregation, namely C(1) and C(2).

Effects of inorganic and organic salts on aggregation behavior of cationic gemini surfactants.

All salts studied effectively reduce critical micelle concentration (CMC) values of the cationic gemini surfactants. The ability to promote the surfactant aggregation decreases in the order of C(6)H(5)COONa > p-C(6)H(4)(COONa)(2) > Na(2)SO(4)> NaCl. Moreover, only C(6)H(5)COONa distinctly reduces both the CMC values and the surface tension at CMC.

Highly fluorescent aggregates modulated by surfactant structure and concentration.

The effects of anionic surfactants on the aggregation-induced emission (AIE) feature of cationic M-silole molecules have been studied. The electrostatic binding of M-silole with the surfactants greatly promotes the aggregation of the mixtures. The M-silole/surfactant aggregates at 1:1 charge ratio exhibit the maximum fluorescence intensity.

Molecular conformation-controlled vesicle/micelle transition of cationic trimeric surfactants in aqueous solution.

Two star-like trimeric cationic surfactants with amide groups in spacers, tri(dodecyldimethylammonioacetoxy)diethyltriamine trichloride (DTAD) and tri(dodecyldimethylammonioacetoxy)tris(2-aminoethyl)amine trichloride (DDAD), have been synthesized, and the aggregation behavior of the surfactants in aqueous solution has been investigated by surface tension, electrical conductivity, isothermal titration microcalorimetry, dynamic light scattering, cryogenic transmission electron microscopy, and NMR techniques. Typically, both the surfactants form vesicles just above critical aggregation concentration (CAC), and then the vesicles transfer to micelles gradually with an increase of the surfactant concentration. It is approved that the conformation of the surfactant molecules changes in this transition process.

Self-assembly of peptide-amphiphile C12-Abeta(11-17) into nanofibrils.

A peptide-amphiphile (C12-Abeta(11-17)) was constructed with a key fragment of amyloid beta-peptide (Abeta(11-17)) attached to dodecanoic acid through an amide bond. The self-assembly behavior of C12-Abeta(11-17) in aqueous solution is studied at 25 degrees C and at pH 3.0 and 10.